This research project has as its primary objective a study of protein combining sites directed against carbohydrate moieties. The proteins under investigation include immune antibodies raised in rabbits against carbohydrate-protein conjugates. The antibodies so obtained are examined their cross reaction with naturally occurring carbohydrate-containing biopolymers (polysaccharides, glycoproteins, glycolipids and bacterial cell wall and cell surface constituents). A second class of proteins being studied are phytohemagglutinins. We are interested in the isolation and purification of these plant agglutinins, their chemical and physical characterization and, most importantly, their interaction with carbohydrates. Phytohemagglutinins are carbohydrate binding proteins of great interest and utility. They are used as models for immune antibodies, differentiating between normal and tumor cells and as probes for investigating cell surfaces. Several phytohemagglutinins are currently under investigation in our laboratory.